Struct FileCoverage 

pub struct FileCoverage {
    pub path: String,
    pub statement_map: BTreeMap<String, Location>,
    pub fn_map: BTreeMap<String, FnEntry>,
    pub branch_map: BTreeMap<String, BranchEntry>,
    pub s: BTreeMap<String, u32>,
    pub f: BTreeMap<String, u32>,
    pub b: BTreeMap<String, Vec<u32>>,
    pub b_t: Option<BTreeMap<String, Vec<u32>>>,
    pub input_source_map: Option<Value>,
    pub x_fallow_function_map: Option<BTreeMap<String, FunctionIdentity>>,
}

Coverage data for a single file. Serializes to Istanbul’s coverage-final.json format.

The root coverage-final.json is a map of file paths to FileCoverage objects.

Fields

path: String

Absolute file path.

statement_map: BTreeMap<String, Location>

Statement locations, keyed by sequential string IDs (“0”, “1”, …).

fn_map: BTreeMap<String, FnEntry>

Function metadata, keyed by sequential string IDs.

branch_map: BTreeMap<String, BranchEntry>

Branch metadata, keyed by sequential string IDs.

s: BTreeMap<String, u32>

Statement hit counts, keyed by the same IDs as statement_map. Istanbul allows null values (e.g., uninstrumented statements); these are coerced to 0.

f: BTreeMap<String, u32>

Function hit counts, keyed by the same IDs as fn_map. Istanbul allows null values; these are coerced to 0.

b: BTreeMap<String, Vec<u32>>

Branch hit counts, keyed by the same IDs as branch_map. Each value is a Vec with one count per branch arm. Istanbul allows null values in both the Vec and individual elements; these are coerced to 0.

b_t: Option<BTreeMap<String, Vec<u32>>>

Branch truthy tracking hit counts. Only present when report_logic is enabled. Tracks whether each operand in a logical expression evaluated to a truthy value. Keyed by the same IDs as binary-expr entries in branch_map.

input_source_map: Option<Value>

Input source map from a prior transformation (e.g., TypeScript to JS). Stored so downstream tools can chain back to the original source. Only present when the instrumenter received an inputSourceMap.

x_fallow_function_map: Option<BTreeMap<String, FunctionIdentity>>

Optional non-Istanbul extension: stable function identity overlay for downstream code-quality tools (Fallow et al.). Keyed by the same IDs as fn_map; ignored by standard Istanbul consumers because the field name is prefixed with x_. Present only when the instrumenter was invoked with InstrumentOptions::function_identity_overlay = true. See the crate-level README’s “X-Fallow function identity” section.

Implementations

impl FileCoverage

pub fn from_json(json: &str) -> Result<FileCoverage, Error>

Deserialize a FileCoverage from a JSON string.

Parses Istanbul-compatible coverage-final.json format. The input should be a single file’s coverage object (not the root map).

pub fn prune_orphan_counters(&mut self) -> usize

Drop counter slots that have no matching location-map entry, enforcing the Istanbul invariant that every counter key is also a key of its location map: keys(s) ⊆ keys(statementMap), keys(f) ⊆ keys(fnMap), and keys(b) / keys(bT) ⊆ keys(branchMap). The x_fallow_functionMap overlay is kept 1:1 with fnMap under the same rule. Returns the total number of orphan entries removed across every map (counter slots plus any orphaned overlay entries), so a non-zero result reliably means the input violated the invariant.

An orphan counter (an s/f/b key whose location-map entry is missing) is fatal to istanbul-lib-coverage’s CoverageMap.merge, which nyc calls to merge sharded coverage: mergeProp looks up statementMap[key] for every s key and passes it to keyFromLoc, which destructures { start } of the undefined entry and throws TypeError: Cannot destructure property 'start' of 'undefined'. A single orphan anywhere aborts the whole nyc report step (issue #107).

Orphans cannot arise from this crate’s own instrumenter output (the counter maps are built from the location-map keys), but a coverage object collected at runtime can pick one up when an upstream instrumenter emitted a counter increment for a location that was later pruned from the map: ++cov.s[id] against an absent slot evaluates undefined + 1 = NaN, which serializes back as null and reappears as an orphan key. Removing the orphan counter is the only valid reconciliation: its location cannot be reconstructed, and Istanbul consumers cannot merge it.

Trait Implementations

impl Clone for FileCoverage

fn clone(&self) -> FileCoverage

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for FileCoverage

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for FileCoverage

fn deserialize<__D>( __deserializer: __D, ) -> Result<FileCoverage, <__D as Deserializer<'de>>::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for FileCoverage

fn serialize<__S>( &self, __serializer: __S, ) -> Result<<__S as Serializer>::Ok, <__S as Serializer>::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.